Method for controlling the operation of a transport system for containers, operating devices and transport system thus controlled

ABSTRACT

A transport system for containers comprises an operating device with linear guide means for the transformation of a uniform circular motion of a motor into a linear harmonic motion with a substantially sinusoidal velocity in a longitudinal direction. The operating device is controlled so as to vary the rotational speed of the motor and to obtain a substantially bell-shaped velocity profile, for gradually accelerating and decelerating the containers so as to obtain a precise advance and positioning thereof without the need for further means for centring the containers.

The present invention relates to a method for controlling the operationof a container transport system. The invention also concerns anoperating device adapted to be controlled by the aforesaid method, andalso a transport system for containers which is thus controlled. Theinvention has been developed with particular regard to a transportsystem of the type in which the containers, disposed in a line andspaced from one another at regular intervals, are moved simultaneouslyand displaced along a predetermined path by a step equal to the distancebetween one container and another, such that each container assumes ateach step the same position as the container which precedes it in line.

Movement systems of the type indicated above are used in installationsin which such containers must reach in progression a series ofpredetermined positions or stations placed along the path. Such systemsare used, for example, in production lines for paints or varnishes inwhich the containers, initially empty, are brought in sequence beneathpaint and colorant dispensing machines, which are arranged to deliverfluid products inside the containers themselves. In installations ofthis type, the containers must frequently be transported along very longpaths, and still arrive precisely at specific positions. It is readilyunderstood that small errors in the positioning of each container ateach individual step of its displacement may result in deviations andshifting of the container from the final position envisaged after acertain number of steps, which shifts may also be considerable becauseof the sum of the individual errors of positioning at each step. Inorder to remedy these problems, many transport systems of the prior artprovide more or less complex centring means in order to guarantee thecorrect positioning of the containers after each advance step.

A transport system for containers which has proved particularlyefficacious is the subject of Patent Application PCT/IT01/00066 of thesame Applicant. In such a transport system, the containers are placed ona modular support structure which extends along the path which thecontainers themselves must travel. Each module of the aforesaid supportstructure comprises a fixed portion, on which are placed the containerslined up in a row, and a movable portion which can be actuated so as toraise the containers from the fixed portion, transport them forwards fora predetermined distance, preferably equal to the pitch between onecontainer and the other, and place them on the fixed portion againbefore returning to the initial position from which to start a newcycle.

In the transport systems of known type, the movement of the containersis obtained by means of systems which comprise cams or connectingrod/crank units. The operating means with cams are generally difficultto produce and do not make it possible to modify the behaviour of thetransport system without modifying the profile of the cam. Moreover, thegradual wearing of the cam results in a corresponding reduction in theaccuracy of operation of the transport system, with the negativeconsequences mentioned above with regard to the positioning of thecontainers.

The transport systems which are operated by means of connectingrod/crank systems generally require very bulky devices in order toobtain the speeds and strokes necessary for effective advancement of thecontainers.

An aim of the present invention is that of providing a method for theoperation of a transport system which solves or prevents the drawbacksmentioned above, and in particular makes it possible to move thecontainers by a precisely predetermined amount without the occurrence ofdeviations or accidental shifts from the position envisaged for eachcontainer at each step of the transport system. Another aim of theinvention is that of providing a method which is simple and economic inexecution.

Yet another aim of the invention is that of providing an operatingdevice which is simple to manufacture and maintain, is compact Andpermits flexible adjustment of the operation of the transport system forthe containers, according to the operating method mentioned above.

A further aim of the invention is that of providing a transport systemadapted to be controlled according to the aforesaid method, andcomprising an operating device of the type mentioned above.

In order to fulfil the aforesaid aims, the present invention has as itssubject a method, an operating device and a transport system as definedin the claims which follow.

Further characteristics and advantages will become clear from thefollowing description of a preferred embodiment, with reference to theappended drawings, provided purely by way of non-limiting example, inwhich:

FIGS. 1, 2, 3 and 4 illustrate diagrammatically a transport system infour different positions, corresponding to as many phases of themovement of a line of containers,

FIG. 5 is a diagrammatic perspective view of an operating devicesuitable for moving the transport system of the preceding figures, and

FIG. 6 is a diagram which shows the preferred course of the velocity inthe principal direct on of displacement of the movable part of thetransport system controlled according to the present invention.

With reference now to the drawings, a transport system for containers,preferably, but not exclusively, of the type which is the subject ofPatent Application PCT/IT01/00066, comprises a support structure 10 witha fixed portion 11, which is for example placed or locked on the groundby means of feet 12. Onto the fixed portion 11 are placed containers 13disposed in a line, spaced from one another by a predetermined amount orpitch P.

The support structure 10 further comprises a movable portion 14, adaptedto be moved in two substantially perpendicular directions X, Z,preferably with the assistance of separate movement devices that can beoperated independently of one another or in combination with each other.The direction X is furthermore substantially parallel to the directionof advance A of the containers 13, which conventionally is directedtowards the right in FIGS. 1 to 4.

The details of production of the support structure 10, like the systemsfor articulated connection of the movable portion 14 to the fixedportion 11, and also the means for raising the movable portion 14 in thedirection Z, are not the subject of the present invention and will nottherefore be discussed further in detail. With regard to the means formoving the movable portion 14 in the direction X, an example isconstituted by the operating device 15 illustrated in FIG. 5, whichcomprises a base framework 16 with two linear guides 17 on which isslidably mounted a carriage 18 which can move in the direction X. Thecarriage 18 may be connected in various ways to the movable portion 14of the support structure 10, for example by way of a bar 19 or by anyother functionally analogous means.

On the carriage 18 a transverse guide 20 is provided for a shuttle 21 orsimilar means, linked to a crank 22 coupled, directly or withtransmission devices interposed, to a motor 23, preferably an electricmotor, the speed of which can be adjusted, for example by way of aninverter (not shown) or similar systems. The crank 22 is operated inrotation by the motor 23 about a substantially vertical axis, K, in thedirection of the arrow R. Purely by way of clarification, the operatingdevice 15 is designed in such a way that uniform rotation of the crank22 effects the reciprocating sliding of the carriage 18 in the directionX, at a velocity V_(x) thereof which over time assumes a sinusoidalcourse, as indicated by the clashed line V in the diagram of FIG. 6,starting from an origin O corresponding substantially to the completelyretracted position of the carriage 18 with respect to the direction ofadvance A of the movable portion 14 of the support structure 10.

In an initial reference state, corresponding to that illustrated in FIG.1, the containers 13 are placed on the fixed portion 14 of the supportstructure 10, aligned in the direction X and spaced from one another bythe predetermined pitch P. In such a state, some containers 13 will bein the optimum position at the end of the operations for which thetransport system is intended. For example, in the case of aninstallation for the production of paints, some containers will belocated beneath dispensing machines which will deliver colorants intothem. Other containers may be located at mixing, labelling, weighing, orpacking stations, and so on, depending on the type and layout of theinstallation.

In the initial state in FIG. 1, the movable portion 14 is disposed belowthe fixed portion 11, in a region of non-interference with thecontainers 13. When it is necessary to move the containers 13 forwardsby a pitch P, the movable portion 14 is first of all pushed upwards inthe direction Z by the known operating means arranged for the purpose,such as to raise the containers 13 vertically from the fixed portion 11,to reach the position illustrated in FIG. 2. At this point, theoperation of the means for movement in the direction X, and inparticular of the operating device 15 of FIG. 5, effects thesubstantially horizontal displacement of the movable portion 14 in thedirection of advance A, for a distance equal to the pitch P, until thestate illustrated in FIG. 3 is reached.

At this point, the movable portion 14 is lowered in the direction Z toreach the position in FIG. 4, in which the containers 13 are againplaced on the fixed stricture 11. In such state, each container 13occupies the same position previously occupied by the container 13immediately preceding it in the line. Further operation of the operatingdevice 15 allows the movable portion 14 to return to the initialposition of FIG. 1.

The operation of the operating device 15 in the direction of advance A,such as to bring the movable portion 14 from the position in FIG. 2 tothat in FIG. 3, occurs in such a way that the velocity of the movableportion 14 in the direction X is obtained according to a lawsubstantially equivalent to that indicated by the continuous curve V₁,with gradually increasing and decreasing acceleration respectively atthe departure position and the arrival position of the movable portion14. This particular velocity curve, preferably obtained by way ofadjustment of the inverter which controls the motor 23, prevents thecontainers 13 from slipping or shifting, because of the inertia, fromtheir predetermined position on the movable portion 14. Moreover, thedisplacement of the movable portion 14 is effected only when the movableportion 14 has completely raised the containers 13 from the fixedportion 11.

Similarly, when the movable portion 14 has reached its forward endposition, illustrated in FIG. 2, the means for movement in the directionX are disabled for a sufficient time t₁ (see FIG. 6) for the movableportion 14 to be lowered to set the containers 13 down on the fixedportion 11 without risk of their slipping or shifting further in thedirection X. The return of the movable portion 14 to the initialposition may take place according to any law of velocity, similar to thelaw V₁ of advance, or more simply with a sinusoidal law V₂, obtainableby operating the motor 23 in uniform rotation.

Finally, during the phases of substantially vertical raising andlowering of the movable portion 14 in the direction Z, the means foroperation thereof in the direction X are disabled and preferablycontribute to maintaining the movable portion 14 in a preciselydetermined horizontal position, while the movement of the movableportion 14 in the direction X, and in particular in the direction ofadvance A of the containers 13, takes place with gradual accelerationand deceleration at the ends of travel, while at the same time keepingthe vertical position of the movable portion fixed, in the direction Z.

The transport system for containers described above and the method forcontrolling its operation make it possible to obtain extremely precisemovement of the containers 13 in the direction of advance A, without theneed to provide centring elements for the containers, even in the casewhere the transport path for the containers themselves is very long.

With the principle of the invention remaining unchanged, the embodimentsand details of production may of course vary widely according to whathas been described and illustrated, without thereby departing from thescope of the present invention.

1. A method for controlling the operation of a transport system forcontainers, of the type comprising a support structure (10) with atleast one fixed portion (11) and a movable portion (14), the containers(13) being disposed in a line on the fixed portion (11), spaced from oneanother at a predetermined pitch (P), the method comprising thefollowing steps: raising the movable portion (14) parallel to a firstdirection (Z) in order to raise the containers (13) from the fixedportion (11); advancing the movable portion (14) parallel to a seconddirection X for a predetermined distance (P)′, with gradual accelerationand deceleration at the beginning and the end of the forward travel,respectively; lowering the movable portion (14) parallel to the firstdirection (Z) in order to place the containers (13) on the fixed portion(11) again; retracting the movable portion (14).
 2. A method accordingto claim 1, wherein the first direction (Z) is substantially vertical,and the second direction (X) is substantially horizontal.
 3. A methodaccording to claim 1, wherein the predetermined distance of advance ofthe movable portion (14) is substantially equal to the pitch (P) betweenone container (13) and another.
 4. A method according to claim 1,wherein the velocity (V_(x)) of the movable portion (14) over time (t),at least in the phase of advance parallel to the second direction (X),is substantially representable by the curve V₁, of FIG.
 6. 5. Anoperating device for a transport system for containers, comprising adevice (18) movable in a longitudinal direction (X), adapted to beconnected to the movable portion (14) of the transport system, a motor(23) with an output shaft being operably connected to the movable deviceby means of operating members (20, 21, 22) adapted to transform auniform circular motion of the output shaft of the motor (23) into aharmonic reciprocating motion of the movable device (18), at a velocitywhich is substantially sinusoidal in the longitudinal direction (X). 6.An operating device according to claim 5, comprising a support structure(16) with first linear guide means (17) for the movable device (18),second linear guide means (20, 21) being arranged on the movable device(18) in a substantially orthogonal direction with respect to the firstlinear guide means (17), crank means (22) being connected on one side tothe second linear guide means (20, 21), and on the other side to themotor (23).
 7. An operating device according to claim 5, wherein themotor (23) is an electric motor controlled by an inverter.
 8. Atransport system for containers, comprising a support structure (10)with a fixed portion (11) and a movable portion (14), the movableportion being controlled by at least two separate operating means in twodifferent directions (X, Z), the second direction X being substantiallyparallel to a predetermined direction of advance (A) of the containers(13), the operating means (15) for the control of the movable portion(14) in the second direction X being adjustable in velocity.
 9. Atransport system according to claim 8, wherein the operating means (15)comprise an electric motor (23) controlled by an inverter.
 10. Atransport system according to claim 8, wherein the operating means (15)are connected to the movable portion (14) and are formed in such amanner that constant rotation of the electric motor (23) results in amovement of the movable portion (14) at a substantially sinusoidalvelocity in the second direction (X), the electric motor (23) beingoperated, in use, so that its rotation speed is constant at least in thestate of operation of the movable portion (14) in the second direction(X) 11-12. (Cancelled)
 13. A transport system according to claim 8,comprising an operating device comprising a device (18) movable in alongitudinal direction (X), adapted to be connected to the movableportion (14) of the transport system, a motor (23) with an output shaftbeing operably connected to the movable device by means of operatingmembers (20, 21, 22) adapted to transform a uniform circular motion ofthe output shaft of the motor (23) into a harmonic reciprocating motionof the movable device (18), at a velocity which is substantiallysinusoidal in the longitudinal direction (X).
 14. A transport systemaccording to claim 13, comprising a support structure (16) with firstlinear guide means (17) for the movable device (18), second linear guidemeans (20, 21) being arranged on the movable device (18) in asubstantially orthogonal direction with respect to the first linearguide means (17), crank means (22) being connected on one side to thesecond linear guide means (20, 21), and on the other side to the motor(23).
 15. A transport system according to claim 14, wherein the motor(23) is an electric motor controlled by an inverter.